This dramatic image offers a peek inside a 'cavern' of dust and gas where thousands of stars are forming. The image, taken by the Advanced Camera for Surveys (ACS) aboard NASA's Hubble Space Telescope, represents the sharpest view ever taken of this region, called the Orion Nebula. More than 3000 stars of various sizes appear in this image. Some of them have never been seen in visible light.

The Orion Nebula is 1500 light-years away, the nearest star-forming region to Earth. Astronomers used 520 Hubble images, taken in five colours, to make this picture. They also added ground-based photos to fill out the nebula. The ACS mosaic covers approximately the apparent angular size of the full Moon. Thes observations were taken between 2004 and 2005.